The invention relates to marine propellers, and more particularly to a foldable triple-bladed marine propeller which does not require any mechanical means to operate. This folding propeller works off of the natural flow of the moving water under the boat when the boat engine is disengaged.
This invention also features a triangular shaped hub to which the propeller blades fasten onto the sides of the hub. This improvement reduces drag and improves symmetry around the drive shaft.
Several patents have been discovered by applicant to be pertinent to the instant application. They are U.S Pat. No. 1,491,512; 1,851,513; 123,733; 997,884; 725,097; 598,337; 3,709,634; and British patent Nos. 2,356 and 116,009. These patents teach various means to collapse or fold blades on two, three, and four propeller assemblies through mechanical means. Only British patent No. 116,009 teaches collapse or folding of the propeller blades by natural forces. However, British patent No. 116,009 is readily distinguishable from the Trumbly invention.
British patent No. 116,009 teaches a similar marine propeller device which collapses or folds by natural forces. However, patent No. 116,009 is distinguishable from the present invention in that the present invention teaches three separate and foldable blades connected to the three sides of the triangular shaped hub. The present invention allows the three separate, foldable blades to fold symmetrically around the drive shaft and triangular hub, thus reducing drag, when the propeller is not in use, more effectively than patent # 116,009. Patent # 116,009 does not anticipate the triangular hub and three separate, foldable propeller blades, but rather teaches an "enlarged portion at the after end of the tail shaft" to which propeller blades are attached. In the case of four bladed propellers the blades are in pairs; for three bladed propellers, two of the blades are a solid inseparable device; consequently patent # 116,009 cannot attain the symmetry of the present invention. The solid pairs of blades anticipated in patent # 116,009 cannot fold to fit closely around the drive shaft, thus producing more drag and less efficiency than the present invention.